X11 beta? What is that?

X11 is the windowing system used by many Unix based systems. With it, a lot of the open source/freeware applications become usable on Mac OS.

This includes things like gimp (Photoshop like utility), the current version of Open Office for Mac OS, and many other applications.

Yes, "Unix based" includes Linux.

I was surprised about they did not present it at the keynote, i consider it as a big important step. X11 is working sweet taking advantage of the quartz rendering now.
anyway you can get more infos on the following websites:
http://www.ppcnerds.org <-- they have a news and some good links for the apple X11
http://www.opendarwin.org <-- they are part of apple members working on the open-source side
http://www.xdarwin.org <-- another good project

I agree, integrated X11 promises to make thousands more apps available to ordinary OS X users. I really hope Apple add virtual desktop support to the OS X desktop. If you haven't used virtual desktops you don't know what you're missing, they are one of the best features of X11 window managers (like Window Makers and FVWM).

For example you could keep photoshop open on one desktop, a web browser and text editor in another, etc. Allows you to quickly switch between desktops laid out and ready to use. No more minimising and unminimising all the time or cluttered desktops.

Virtual desktop wouldn't be hard to implement and it can be an optional feature for those who prefer one desktop.

If you want virtual desktops in OS X, there are many ways to get it. The free way is to download a program called Space, which I believe you'll find on sourceforge.